There is little doubt of islet engraftment feasibility after the results demonstrated by the Edmonton protocol, but disappointing reliability of the procedure has curbed more widespread clinical application for a diabetes cure. Markedly improved conditions to optimize engraftment reliability must be pursued. The long-term goal of this proposal is to monitor live-cell physiology, including beta cell mass and glucose-releasable insulin content during three stages of islet engraftment procedures. We believe that one centerpiece in developing islet allograft therapy for curing diabetes is the ability to monitor the major markers of insulin secretory function pre-engraftment, within 24 hours of engraftment, and over the remaining lifetime of the graft. In order to achieve the detailed cellular knowledge we will dovetail parallel human and mouse model transplant programs. The specific aims are to: (1) Translate our live-cell fluorescent monitoring of insulin secretory granule function from mouse to cadaveric human islets at the pre-engraftment stage. (2) Identify functional and structural markers of cadaveric beta cells that correlate with healthy, phasic glucose stimulated insulin secretion. (3) Engraft and monitor cadaveric islets expressing our live-cell fluorescent insulin reporters in diabetic NOD-SCID models containing our novel body window. The body window will allow us to noninvasively study at will the cellular function and structures of the graft throughout the engraftment period. Major markers of secretory function will be positively, and negatively, correlated with successful engraftment outcomes in the mouse model. The knowledge from these studies can be applied to improve reliability of clinical engraftments.